With the increasing demand for quick, hot snacks and so called "fast food", there is an increasing requirement to be able to process frozen pre-cooked foodstuffs ready for consumption. In particular, it is necessary to be able to heat up from the frozen condition a pre-cooked foodstuff to a serving temperature in the shortest possible time, and typically a temperature change from -17.degree. C. to +74.degree. C. must be achieved. Preferably the time should be as short as possible, and ideally should be well under one minute.
Conventional microwave ovens are not particularly well suited to this function, and it has been proposed to concentrate the available energy by providing a reflecting surface within a chamber into which microwave energy is transmitted so that the latter is focused generally into the region of the chamber in which the foodstuff is located. In this way the energy is concentrated into the foodstuff and the latter is raised in temperature at the maximum possible rate.
It is an object of the present invention to provide a more convenient heating chamber for certain foodstuffs.